The related art proposes a technology in which an electric power steering apparatus includes a torque sensor (a relative angle detection apparatus), and an electric motor is controlled based on a value detected by the torque sensor.
For example, the torque sensor disclosed in JP-A-2009-255645 has the following configuration. That is, the torque sensor is configured to have a torsion bar that coaxially connects an input shaft and an output shaft; a ring-shaped magnet that is attached to an end portion of the input shaft; a pair of magnetic yokes that are attached to an end portion of the output shaft; and a magnetometric sensor that detects magnetic flux density occurring in the magnetic yokes.